Method and system for reducing degradation loss of flue gas carbon capture absorption solvent

Abstract

The present application relates to the field of carbon dioxide capture, and discloses a method and system for reducing degradation loss of flue gas carbon capture absorption solvent, comprising stripping oxygen from the absorption solvent rich solution to obtain oxygen-containing stripping gas and spent absorption solution; the spent absorption solution is regenerated to obtain regenerated gas and absorption solvent lean solution, wherein at the same time, the oxygen-containing stripping gas is used to extract the regenerated gas, the method provided by the present application adds a stripping oxygen removal step, first strips oxygen from the CO2-rich absorption solvent rich solution after absorption, and regenerates the oxygen physically dissolved in the absorption solvent rich solution, thereby reducing the oxygen concentration in the absorption solvent, and further reducing the possible degradation reaction, then using the obtained oxygen-containing stripping gas to extract the regenerated gas during regeneration, reducing the operation pressure during regeneration to reduce the operation temperature, thereby reducing the degradation reaction rate, and achieving the purpose of reducing the degradation loss of flue gas carbon capture absorption solvent.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, specifically to a method and system for reducing solvent degradation losses during carbon capture and absorption in flue gas. Background Technology

[0002] The combustion of fossil fuels is currently the primary way humans obtain energy, and the flue gas produced by this combustion is the main source of CO2 emissions, accounting for more than 70% of total CO2 emissions. Therefore, the use of carbon dioxide capture, utilization, and storage (CCUS) technology to treat flue gas has become a focus of attention across various industries.

[0003] Based on different CO2 separation principles, CO2 capture technologies can be divided into four types: absorption, adsorption, membrane separation, and cryogenic distillation. Currently, absorption, represented by organic amines, is the most widely used technology in the field of flue gas carbon capture. However, organic amines undergo degradation reactions during use, leading to continuous consumption and persistently high capture costs. Therefore, reducing solvent degradation losses in flue gas carbon capture absorption has become an urgent problem to be solved in this field.

[0004] CN01138009.8 discloses an antioxidant that inhibits the oxidative degradation of low partial pressure CO2 recovery solvent, wherein the antioxidant is a metal oxide and its salt.

[0005] CN202010898314.3 discloses a class of α-amino acid salt absorbents for capturing carbon dioxide, comprising α-amino acid salts, a solubilizing solvent, an absorbent, and water, wherein the volume ratio of the α-amino acid salt is 15%-40%, the volume ratio of the solubilizing solvent is 5%-15%, and the volume ratio of the absorbent is 2%-8%.

[0006] CN201710219069.7 discloses a novel method to suppress solution degradation and high viscosity of the carrier phase in phase change absorbents during the removal of acidic gases. This method achieves antioxidant and degradation-resistant effects by adding a certain proportion of alcohol or water to the main absorbent (organic amine and polyether). When the phase change absorbent is homogeneous, the additive dissolves well, providing protection. After the phase change absorbent removes acidic gases, the solution forms a carrier phase and an organic phase. The additive can still dissolve separately in both phases in a phase equilibrium manner, providing excellent protection for both the organic and carrier phases.

[0007] As can be seen from the above, existing technologies mainly focus on reducing the oxidative degradation of solvents, specifically through two approaches: adding antioxidants and developing solvents with better antioxidant properties. Research on reducing the degradation of carbon capture solvents from a process perspective is extremely limited. Summary of the Invention

[0008] The purpose of this invention is to overcome the problem of solvent loss due to easy degradation of solvents in flue gas carbon capture and absorption processes, and to provide a method and system for reducing solvent degradation loss in flue gas carbon capture and absorption processes. This method involves gas stripping to remove oxygen and regenerating the rich absorbent solvent, with extraction during regeneration. This reduces both the oxygen concentration in the absorbent solvent and the operating temperature of the regeneration reaction, thereby significantly reducing solvent degradation loss in flue gas carbon capture and absorption processes, and has broad application prospects.

[0009] To achieve the above objectives, a first aspect of the present invention provides a method for reducing solvent degradation loss during flue gas carbon capture and absorption, comprising the following steps:

[0010] (1) After removing oxygen from the rich solution of the absorption solvent by gas stripping, oxygen-containing gas stripping and ready-to-be-generated absorption solution are obtained.

[0011] (2) The absorbent solution to be regenerated is regenerated to obtain regenerated gas and a lean absorbent solution, wherein the regenerated gas is extracted using the oxygen-containing gas extraction.

[0012] A second aspect of the present invention provides a system for reducing the degradation loss of carbon capture and absorption solvents in flue gas, wherein the system includes a stripping deoxygenation tower, a regeneration tower, and a Venturi injector. The stripping deoxygenation tower has a liquid inlet at the top, an air inlet at the bottom, and a solvent-rich liquid outlet at the bottom. The solvent-rich liquid outlet is connected to the regeneration tower, the air outlet at the top of the regeneration tower is connected to the feed inlet of the Venturi injector, and the airflow inlet of the Venturi injector is connected to the stripping gas outlet at the top of the stripping deoxygenation tower.

[0013] The above technical solution adds a gas stripping deoxygenation step. First, the CO2-rich absorbent solvent is stripped to remove oxygen, which regenerates the oxygen physically dissolved in the absorbent solvent, reducing the oxygen concentration in the absorbent solvent and thus reducing the possibility of degradation reaction. Then, the oxygen-containing stripped gas is used to extract the regeneration gas during regeneration. By reducing the operating pressure during regeneration, the regeneration operating temperature is lowered, thereby reducing the degradation reaction rate and achieving the goal of reducing the degradation loss of the flue gas carbon capture and absorption solvent. Attached Figure Description

[0014] Figure 1 This is a flowchart of Example 1;

[0015] Figure 2 This is a flowchart of Comparative Example 1.

[0016] Explanation of reference numerals in the attached figures

[0017] 1-Pretreatment tower; 2-Absorption tower; 3-Regeneration tower; 4-Gas stripping deoxygenation tower; 5-CO2 compressor; 6-CO2 gas ejector; 7-Demister; 8-Heat exchanger; 9-Lean liquor pump; 10-Lean liquor cooler; 11-Regeneration gas condenser separator; 12-Rich liquor pump; 13-Washing pump; 14-Washing water cooler; 15-Fan; 16-Reboiler; 17-Pretreatment pump; 18-Pretreatment cooler; 19-Venturi ejector; 101-Raw material flue gas; 102-Purified gas; 103-Product gas; 104-CO2 reflux pipe. Detailed Implementation

[0018] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0019] In this invention, "absorption solution to be generated" refers to the rich solution of absorption solvent after O2 has been extracted by gas.

[0020] The first aspect of this invention provides a method for reducing solvent degradation loss during carbon capture and absorption in flue gas, comprising the following steps:

[0021] (1) The oxygen-rich absorbent solvent is stripped to obtain oxygen-containing stripping gas and ready-to-be-generated absorbent solution.

[0022] (2) The absorbent solution to be regenerated is regenerated to obtain regenerated gas and a lean absorbent solution, wherein the regenerated gas is extracted using the oxygen-containing gas extraction.

[0023] In some embodiments of the present invention, preferably, externally added CO2 is used as the stripping gas during the stripping deoxygenation process; wherein the pressure of the stripping deoxygenation is 0.6-2.5 MPaA, preferably 0.8-1.5 MPaA. The CO2 pressure during stripping deoxygenation affects the size of the bubbles formed by the jet regeneration, thereby affecting the gas-liquid contact area and thus the separation effect. The CO2 pressure can be any value within the range of any two of 0.6 MPaA, 1.0 MPaA, 1.5 MPaA, 2.0 MPaA, and 2.5 MPaA, or any value within the range of any two of 0.8 MPaA, 1.0 MPaA, 1.2 MPaA, and 1.5 MPaA.

[0024] In some embodiments of the present invention, preferably, the regeneration pressure is 10-50 kPaA, more preferably 20-40 kPaA. The regeneration pressure affects the regeneration operation temperature, and thus affects the degradation rate of the absorbent solvent. The regeneration pressure can be any value within the range of any two of the following: 10 kPaA, 20 kPaA, 30 kPaA, 40 kPaA, and 50 kPaA; or any value within the range of any two of the following: 20 kPaA, 25 kPaA, 30 kPaA, 35 kPaA, and 40 kPaA.

[0025] In some embodiments of the present invention, preferably, the gas obtained after extraction is a carbon capture product.

[0026] In some embodiments of the present invention, preferably, the carbon capture product is used for the air stripping deoxygenation.

[0027] In some embodiments of the present invention, preferably, during the stripping deoxygenation process, the amount of externally added CO2 is 1-20 wt% of the carbon capture product. During the stripping deoxygenation process, CO2 is used as the stripping gas, or a portion of the carbon capture product can be recycled as the stripping gas. In this case, the amount of externally added CO2 is 1-20 wt% of the total amount of the carbon capture product. The greater the reflux rate of carbon dioxide from the carbon capture product, the better the stripping deoxygenation effect, but this will cause a loss in product gas pressure, increase compression work, and if the amount of refluxed CO2 is too large, the effect on increasing the stripping effect will not be significant. Therefore, within the above range, when the amount of CO2 used in stripping deoxygenation can be any value within any two of the following ranges (1 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt% of the total carbon capture product), the product pressure loss can be relatively small while ensuring the gas deoxygenation effect.

[0028] A second aspect of the present invention provides a system for reducing solvent degradation losses in flue gas carbon capture and absorption, such as... Figure 1 As shown, the system includes a stripping deoxygenation tower 4, a regeneration tower 3, and a Venturi ejector 19. The stripping deoxygenation tower 4 has a liquid inlet at the top, an air inlet at the bottom, and a solvent-rich liquid outlet at the bottom. The solvent-rich liquid outlet is connected to the regeneration tower 3. The air outlet at the top of the regeneration tower 3 is connected to the feed inlet of the Venturi ejector 19. The airflow inlet of the Venturi ejector 19 is connected to the stripping gas outlet at the top of the stripping deoxygenation tower 4.

[0029] In some embodiments of the present invention, preferably, the outlet of the Venturi ejector is connected to a CO2 reflux pipe, the other end of which is connected to the air inlet at the bottom of the stripping deoxygenation tower. The gas exiting the Venturi ejector is the carbon capture product, and using the obtained carbon capture product as the gas during stripping deoxygenation eliminates the need for additional gas supply.

[0030] In some embodiments of the present invention, preferably, the CO2 returned to the stripping deoxygenation tower via the CO2 reflux pipe is used for stripping deoxygenation, and the amount of externally added CO2 used in the stripping deoxygenation process is 1-20 wt% of the amount of carbon capture product discharged from the Venturi injector.

[0031] In some embodiments of the present invention, preferably, the pressure at the top of the regeneration tower 3 is set to 10-50 kPaA, more preferably 20-40 kPaA.

[0032] In some embodiments of the present invention, preferably, the air inlet at the lower part of the stripping deaerator is used to supply CO2, and the pressure of the CO2 is set to 0.6-2.5 MPaA, preferably 0.8-1.5 MPaA.

[0033] In some embodiments of the present invention, preferably, an absorption tower is also included, the liquid outlet of which is connected to the liquid inlet of the stripping deoxygenation tower.

[0034] Preferably, the diameter of the stripping deoxygenation tower is 1 / 10 to 4 / 5 of the diameter of the absorption tower, and more preferably 3 / 10 to 3 / 5. The choice of tower diameter affects the gas-liquid distribution, and thus the separation effect. The diameter of the stripping deoxygenation tower can be any value within the range of any two of the following values: 1 / 10, 1 / 5, 3 / 10, 2 / 5, 5 / 10, 3 / 5, 7 / 10, and 4 / 5 of the absorption tower diameter.

[0035] Preferably, the height of the stripping deoxygenation tower is 1 / 6 to 2 / 3 of the height of the absorption tower, and more preferably 1 / 3 to 1 / 2. The choice of tower height affects the mass transfer area, and thus the separation effect. The height of the stripping deoxygenation tower can be any value within the range of any two of the following values: 1 / 6, 1 / 5, 1 / 4, 1 / 3, and 2 / 3 of the absorption tower height. Alternatively, it can be any value within the range of any two of the following values: 1 / 3, 2 / 5, and 1 / 2.

[0036] Combination Figure 1 The system operation process of the present invention is described as follows:

[0037] The raw flue gas 101 enters the absorption tower 2 after being purified and cooled by the pretreatment tower 1. In the absorption zone of the absorption tower 2, it comes into contact with the lean absorbent solvent, causing the CO2 in the raw flue gas to be transferred into the absorbent solvent, resulting in a CO2-rich absorbent solvent. The rich absorbent solvent is drawn out from the bottom of the absorption tower 2 and enters the stripping deoxygenation tower 4 via the rich solvent pump 12. The CO2 gas ejector 6 in the stripping deoxygenation tower 4 sprays out high-concentration CO2, which comes into countercurrent contact with the rich absorbent solvent. The high-concentration CO2 gas is used to remove the O2 gas from the rich absorbent solvent, resulting in oxygen-containing stripped gas and the absorbent solution to be generated.

[0038] After the O2 is stripped, the absorbent solution is sent to the regeneration tower 3 after heat exchange in the heat exchanger 8. The reboiler 16 heats the regeneration tower 3. Through the action of stripping and heating, the CO2 in the absorbent solution is regenerated, and regeneration gas and lean absorbent solvent are obtained. During the regeneration, the oxygen-containing stripped gas is demisted by the demister 7 and sent to the Venturi ejector 19 at the top of the regeneration tower 3 to extract the regeneration gas in the regeneration tower 3, and carbon capture product is obtained. A portion of the carbon capture product is compressed and pressurized (CO2 compressor 5) and sent to the stripping deoxygenation tower 4 for stripping deoxygenation. The majority is sent to the subsequent liquefaction unit as product gas 103.

[0039] After the lean solvent is drawn from the bottom of the regeneration tower 3, it is cooled by the heat exchanger 8 and then sent by the lean solvent pump 9 to the lean solvent cooler 10 before entering the absorption tower 2 for recycling. The liquid in the bottom of the pretreatment tower 1 is drawn from the pretreatment pump 17 and cooled by the pretreatment cooler 18 before re-entering the pretreatment tower 1 for recycling.

[0040] After the flue gas comes into contact with the lean absorbent solvent in the absorption zone of the absorption tower 2, it rises further and enters the lower part of the washing zone of the absorption tower 2 through the gas lift cap. After contacting the washing liquid, the purified gas 102 is discharged from the top of the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the washing zone for recycling.

[0041] The method and system provided by this invention have the following advantages:

[0042] (1) No need to change the solvent formulation, no consumption of antioxidants, and the degradation loss of flue gas carbon capture solvent can be significantly reduced simply by optimizing the process flow;

[0043] (2) By bringing pressurized high-concentration CO2 gas into contact with the rich absorbent solvent, the acid load in the rich absorbent solvent entering the regeneration tower can be increased, thereby increasing the driving force of the regeneration reaction and reducing the difficulty of the regeneration reaction.

[0044] (3) By extracting the regenerated gas, the operating temperature of the regeneration tower can be reduced, and waste hot water can be used for heating during regeneration, thereby reducing the energy consumption cost of regeneration.

[0045] Example 1

[0046] Taking a complex amine solvent as the absorption solvent as an example, the absorption solvent comes from MA-2 of Sinopec Nanjing Chemical Research Institute Co., Ltd., according to... Figure 1 The process shown describes the method for capturing carbon in flue gas and degrading the widely used absorption solvent as follows:

[0047] (1) After the raw flue gas 101 is treated by the pretreatment tower 1, the flue gas is sent from the top of the pretreatment tower 1 to the bottom of the absorption tower 2 by the blower 15. The liquid at the bottom of the pretreatment tower 1 is drawn out by the pretreatment pump 17 and cooled by the pretreatment cooler 18 before re-entering the pretreatment tower 1 to contact the newly entered raw flue gas 101 to remove impurities and cool down the raw flue gas 101.

[0048] (2) The pretreated flue gas comes into contact with the lean absorbent solvent in the absorption zone of the absorption tower 2, so that the CO2 in the flue gas is transferred to the absorbent solvent to obtain a CO2-rich absorbent solvent. The flue gas rises further in the absorption tower 2 and enters the lower part of the washing zone of the absorption tower 2 through the gas lift cap. After contacting the washing liquid, the purified gas 102 is discharged from the top of the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the washing zone for recycling.

[0049] (3) The CO2-rich absorption solvent is drawn from the bottom of the absorption tower 2 and sent to the inlet of the stripping deoxygenation tower 4 by the rich liquid pump 12. The gas inlet at the bottom of the stripping deoxygenation tower 4 is connected to the CO2 reflux pipe 104. The refluxed CO2 is ejected through the gas ejector 6. The refluxed CO2 comes into contact with the absorption solvent, causing the oxygen in it to be transferred into the CO2 to obtain oxygen-containing stripping gas and the absorption solution to be generated.

[0050] Among them, the diameter of the stripping deoxygenation tower 4 is 1 / 5 of the diameter of the absorption tower 2, the tower height is 1 / 6 of the height of the absorption tower 2, the amount of CO2 entering the stripping deoxygenation tower 4 is 2% of the carbon capture product, and the pressure is 0.6 MPaA.

[0051] (4) The absorbent solution to be generated flows out from the rich absorbent solvent outlet at the bottom of the stripping deoxygenation tower 4, is heated by the heat exchanger 8 and sent to the regeneration tower 3. The reboiler 16 heats the regeneration tower 3 to regenerate the CO2 in the absorbent solution to obtain regeneration gas and lean absorbent solvent.

[0052] The oxygen-containing stripped gas obtained from the top of the stripping deoxygenation tower 4 is sent to the gas flow inlet of the Venturi ejector 19 after the entrained liquid droplets are removed by the demister 7. The regeneration gas in the regeneration tower 3 enters the feed inlet of the Venturi ejector. The regeneration gas in the regeneration tower 3 is extracted by the oxygen-containing stripped gas, so that the pressure at the top of the regeneration tower 3 is maintained at 45 kPaA. The combined gas of regeneration gas and oxygen-containing stripped gas is obtained from the discharge port of the Venturi ejector 19, which is the carbon capture product. The carbon capture product is condensed and separated into liquid by the regeneration gas condenser 11 to obtain high-concentration CO2 gas. After being pressurized by the compressor 5, 98 wt% is sent to the subsequent liquefaction unit as product gas 103, and 2 wt% is sent to the stripping deoxygenation tower 4 through the CO2 return pipe 104.

[0053] (5) The regenerated lean absorbent solvent is drawn from the bottom of the absorption tower 3, first through the heat exchanger 8 to recover heat, then through the lean solvent cooler 10 to cool down, and then returned to the absorption zone of the absorption tower 2 for recycling.

[0054] Calculations show that, using the method of this embodiment, the solvent degradation loss is approximately 44% of that in Comparative Example 1.

[0055] Example 2

[0056] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0057] Example 3

[0058] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0059] Example 4

[0060] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0061] Example 5

[0062] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0063] Example 6

[0064] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0065] Example 7

[0066] The implementation is carried out in the manner of Example 1, except that the CO2 reflux flow rate, reflux pressure, tower diameter and tower height of the stripping deoxygenation tower 4, and regeneration pressure of the regeneration tower 3 are different, as detailed in Table 1.

[0067] Table 1 Parameters of each embodiment

[0068]

[0069]

[0070] Comparative Example 1

[0071] like Figure 2 As shown, the absorption solvent is the same as in Example 1, and the specific process is as follows:

[0072] (1) The flue gas 101, after being treated by the pretreatment tower 1, is sent from the top of the pretreatment tower 1 to the bottom of the absorption tower 2 by the blower 15. The liquid at the bottom of the pretreatment tower 1 is drawn out by the pretreatment pump 17 and cooled by the pretreatment cooler 18 before re-entering the pretreatment tower 1. It then contacts the newly entered raw flue gas 101 to remove impurities and cool the raw flue gas 101.

[0073] (2) The pretreated flue gas comes into contact with the lean absorbent solvent in the absorption zone of the absorption tower 2, so that the CO2 in the flue gas is transferred to the absorbent solvent to obtain a CO2-rich absorbent solvent. The flue gas rises further in the absorption tower 2 and enters the lower part of the washing zone of the absorption tower 2 through the gas lift cap. After contacting the washing liquid, the purified gas 102 is discharged from the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the absorption zone for recycling.

[0074] (3) The CO2-rich absorption solvent is drawn from the bottom of the absorption tower 2, heated by the heat exchanger 8, and sent to the regeneration tower 3. Under normal pressure, the CO2 in the rich solution is regenerated by the action of gas stripping and heating.

[0075] (4) After the regenerated CO2 gas is condensed and separated into liquid by the regenerated gas condenser 11, a high concentration of CO2 gas is obtained. After being pressurized by the compressor 5, all of it is sent to the subsequent liquefaction unit as product gas 103. After the regenerated absorbent lean liquid is drawn out from the bottom of the regeneration tower 3, it first recovers heat through the heat exchanger 8, then cools down through the lean liquid cooler 10, and returns to the absorption zone of the absorption tower 2 for recycling.

[0076] Comparative Example 2

[0077] The procedure is carried out in accordance with Example 1, with the main difference being the diameter and height of the stripping deoxygenation tower.

[0078] Comparative Example 3

[0079] The procedure is carried out in accordance with Example 1, with the main difference being the diameter and height of the stripping deoxygenation tower.

[0080] The results of solvent loss in Examples 1-7 and Comparative Examples 1-3 are shown in Table 2.

[0081] Table 2 Solvent Absorption Loss

[0082] serial number <![CDATA[Degradation loss (kg / t CO2)]]> Degradation loss (percentage of loss in Comparative Example 1, %) Comparative Example 1 0.6 / Comparative Example 2 0.402 67 Comparative Example 3 0.373 62 Example 1 0.264 44 Example 2 0.156 26 Example 3 0.066 11 Example 4 0.114 19 Example 5 0.084 14 Example 6 0.316 53 Example 7 0.088 15

[0083] It is evident that the degradation loss of the absorbent solvent using the method provided by this invention is far lower than that in Comparative Example 1, which did not employ the method provided by this invention. In particular, in Examples 3, 5, and 7, the degradation loss of the absorbent solvent is only 0.066-0.114 kg / t CO2, which is only 11-15% of that in Comparative Example 1. This is because the reflux CO2 pressure, the diameter and height of the stripping deoxygenation tower, and the pressure settings of the regeneration tower are all more reasonable. Their synergistic effect promotes the regeneration of the regenerated solvent and reduces the degradation loss of the absorbent solvent.

[0084] In contrast, Comparative Examples 2 and 3, compared to Example 1, had either excessively large or insufficient column diameters and heights, which affected the separation effect, and their degradation loss rates were even lower than those of Example 1 of the present invention.

[0085] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A system for reducing solvent degradation losses during carbon capture and absorption in flue gas, characterized in that, The system includes a stripping deoxygenation tower, a regeneration tower, and a Venturi ejector. The stripping deoxygenation tower has a liquid inlet at the top, an air inlet at the bottom, and a solvent-rich outlet at the bottom. The solvent-rich outlet is connected to the regeneration tower. The air outlet at the top of the regeneration tower is connected to the feed inlet of the Venturi ejector, and the airflow inlet of the Venturi ejector is connected to the stripping gas outlet at the top of the stripping deoxygenation tower. The outlet of the Venturi injector is connected to a CO2 reflux pipe, and the other end of the CO2 reflux pipe is connected to the air inlet at the bottom of the stripping deaerator. The system also includes an absorption tower, the liquid outlet of which is connected to the liquid inlet of the stripping deoxygenation tower. The diameter of the stripping deoxygenation tower is 3 / 10 to 5 / 10 of the diameter of the absorption tower, and the height of the stripping deoxygenation tower is 1 / 3 to 1 / 2 of the height of the absorption tower. The raw flue gas is sent into the absorption tower for absorption to obtain a rich solution of absorption solvent. The rich solution of absorption solvent is then subjected to stripping deoxygenation in a stripping deoxygenation tower to obtain oxygen-containing stripped gas and a ready-to-be-generated absorption solution. The absorbent solution to be regenerated is regenerated in a regeneration tower to obtain regenerated gas and lean absorbent solvent. Simultaneously, the regenerated gas is extracted using oxygen-containing stripping gas. The extracted gas is a carbon capture product, which is refluxed back to the stripping deoxygenation tower via the CO2 reflux pipe for deoxygenation. The amount of external CO2 used in the stripping deoxygenation process is 5-10 wt% of the amount of carbon capture product discharged from the Venturi ejector. The pressure at the top of the regeneration tower is set to 10-50 kPaA; the air inlet at the bottom of the stripping deoxygenation tower is used to supply CO2, and the pressure of the CO2 entering is set to 0.6-2.5 MPaA.

2. The system according to claim 1, characterized in that, The pressure at the top of the regeneration tower is set to 20-40 kPaA.

3. The system according to claim 1, characterized in that, The incoming CO2 pressure is set to 0.8-1.5 MPaA.

4. A method for reducing solvent degradation loss in flue gas carbon capture and absorption based on the system described in any one of claims 1-3, characterized in that, Includes the following steps: (1) The oxygen-rich absorbent solvent is stripped to obtain oxygen-containing stripping gas and absorbent solution to be generated; (2) The absorbent solution to be regenerated is regenerated in a regeneration tower to obtain regenerated gas and lean absorbent solvent. The regenerated gas is extracted using oxygen-containing stripping gas. The extracted gas is carbon capture product. The carbon capture product is used for gas stripping deoxygenation. During the gas stripping deoxygenation process, external CO2 is used as the stripping gas. The pressure of the gas stripping deoxygenation is 0.6-2.5 MPaA. The amount of external CO2 used is 5-10 wt% of the carbon capture product. The regeneration pressure is 10-50 kPaA.

5. The method according to claim 4, characterized in that, The pressure for the air stripping deoxygenation is 0.8-1.5 MPaA.

6. The method according to claim 4, characterized in that, The regeneration pressure is 20-40 kPaA.

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